L2000 wiring problem. Paging Ken Baker, Spidey, etc.

Discussion in 'G&L Bass Forum' started by Hugh Jass, Jul 25, 2009.

  1. Hugh Jass

    Hugh Jass

    Oct 10, 2008
    Canada eh
    Soooo, 2007 US L2000.

    Just after buying it I discovered that the treble knob didn't work ONLY while in parallel (treble full off). While waiting for G&L to figure out what the heck they were going to do about it, it mysteriously fixed itself while I was experimenting with different pickup heights. A couple times since then it has done the same. It doesn't work when first plugged in, I mess with the Neck pickup height, witchcraft happens, and it works fine.

    Here is the really strange part: I was doing my best at troubleshooting and was doing the screwdriver/polepiece test, and lo and behold the top coil on the bridge pickup seems pretty much dead regardless of any settings . All other coils glean a healthy pop when touched but barely a click on that one coil. Same story regardless of wether parallel is working or not.

    I have had both pickups out of their plastic housings and everything looks fine connection wise. I have thoroughly rooted through the mess of a control cavity and can find no loose wires or broken connections. all grounds seem solid.

    Lately I have also been noticing that I get a bit of a fuzz when playing low notes regardless of volume. May be related? Yes it has a new battery. The treble pot has also been replaced to no avail.

    I have still not been contacted by G&L regarding the original issue (which occured in april) and have not heard anything good regarding their customer service.

    If any of you have any insight I would be forever grateful. :D


    - When in parallel mode treble control works intermittently (pot has been replaced with no effect).

    - Top coil on bridge pickup dead.

    - Slight fuzz when playing low notes regardless of volume.

    - No visible loose connections.

    - New battery.

    - All other settings (i.e. active/passive/boost/pu selector/bass/treb/vol) have no effect on these problems.

    P.S. I know how to solder.
  2. If you're the original owner, check your warranty status.

    That's just plain weird. Assuming that the thing was wired correctly, there's no way for the treble control to only work in parallel mode. The tone and volume controls are completely downstream from the pickups and their switching.

    Part of me would say that you've got a failed coil. However, considering what you've said about the treble control, all bets are off until the coil is isolated and checked. I'd completely disconnect the pickups from the series/parallel switch and measure the DC resistance of each coil in ohms. All four coils should be essentially equal. Any value that is notably off would be suspect. If the coil is indeed dead, you can either replace the whole pickup or have it repaired. I'd call some good pickup people before I'd replace it.

    How solder connections look and how they well work can be different; cold solder joints like to hide. You could also have a conductor broken inside its insulation and not even see it, though you could feel it by wiggling the wire long its length.

    At this point, I wouldn't trust anything. Download and print my wiring diagram and use it to "proof" the wiring in your bass. Alternately, you can use it to completely re-wire your bass if you'd like. If the wiring looks okay, you might heat up the connections to reset them.

    Could be a failed or failing chip on the preamp board. Could also be a thoroughly mucked up jack. Does this happen if you pull the battery? How about if you pull the chip (it's socketed)? If the "fuzz" problem persists with either or both pulled, the jack becomes suspect.

    Sadly, this isn't atypical. I'd recommend that you post your customer service experience at Guitars By Leo. You might get their attention by posting at a location where a little bit of attention is paid (this ain't it). I'm not a G&L employee, so I can't do anything more than raise the same sort of ruckus that you can raise.

    That's a good thing! At least so long as you don't use some great big ol' soldering gun! :D

  3. Hugh Jass

    Hugh Jass

    Oct 10, 2008
    Canada eh
    Thanks for the quick reply!

    Just the opposite, treble works fine in everything except parallel (It sounds fully rolled off). But you are right in how little sense it makes considering that the pots should be the last things to shape the signal.

    I do still have a warranty but the guy I bought the bass off of no longer works at the shop. Their "tech" guy who I have dealt with there seems to be completely incapable of making any kind of decision and at the moment he is the only "bass" person. I snapped a bit at him last time I was there after he gave me the runaround for 45 minutes and wouldn't listen. Now he doesn't seem to want to help me (I am really an extremely calm person). I think I will leave a message with the "never there" manager.

    Anyway, even if G&L decides to take a look at it, it sounds like it would be gone for months. Maybe on my days off I will gut the whole thing and rewire it from scratch (cleaning up the wiring while I'm in there) I do know how to solder but don't know much about circuit testing / checking resistance and the like. I was thinking that I should probably check every wire while I have it out. Any tips? That wiring diagram looks great and I will print it off when I get home tonight.

    Would any guitar shop be able to test that pickup? There is a place called "Guitar O.R." here in town but it is a long drive I would rather not make.

    Thanks again!
  4. I knew that.... :rolleyes:

    The G&L warranty is to the original purchaser. They've been known to fudge on that, but there's no way of knowing when or if.

    If you don't have one already, buy a simple multimeter, either analog or digital. This is the tool to use for measuring the DC resistance of the pickup coils. The instructions will give you the basics on use. You'd then connect the meter to the black and white leads of a pickup and see how it reads. Then the green and yellow leads. Repeat for the other pickup. All the measurements should match or be very close.

    To do it properly, the pickups should be removed, or isolated, from the rest of the circuit. While "Guitar O.R." may be able to do that, you can as well.

    Give G&L another jiggle and see if they grunt. If no response, dig in.

  5. Hugh Jass

    Hugh Jass

    Oct 10, 2008
    Canada eh
    Multimeter eh? I will have to stop by Circuit City after work (Canada's Radio Shack). Can it be used to test wire conduction / potentiometer function etc ? I have only ever used an automotive circuit tester (12v)

    I am the original purchaser on the bass. The guy I was talking about was the only one who dealt with basses in the store and is now gone. Kinda done with that store. I am just not willing to go through the headache of dealing with all the runaround and losing the bass for months to try to claim warranty on it. Maybe if it was the neck or something like that.

    I like learning new skills so I think a gut and rewire is in order here. Perhaps this would be a good excuse to do the single coil conversion that seems so popular? I was thinking I would remove everything, sand down all the solder, shorten all the waaay to long wires, test everything for conduction (or resistance) and put it all back together as per your wiring diagram. Maybe even shield it while I am in there. Do you just ground the shielding to the bridge with everything else or does it have to be grounded seperately?

    Thanks Ken, your the G&L King! :D
  6. Yup. They used to be called Volt-Ohm Meters, or VOMs, a few years ago. Now it's multimeter. They are more capable than a simple circuit tester, though there are limits. Do read the instructions.

    As much a pain as it is, and as much a pain as G&L can sometimes be to wake up, I'd still recommend that you explore the warranty route. The USA basses come with a 10 year warranty. Unless the warranty has specific language for Canada, you should be covered.

    You should understand that digging around in the cavity doing your own repair could void the warranty. G&L is usually pretty flexible, but there are limits.

    The control cavity of an L series G&L is a pretty tough learning ground, but you'll probably be okay if you go slow and be careful. You might also do well to keep it stock at least for a while. Those long leads are a pain, but kind of necessary due to the non-modular way that G&L builds the circuit, so don't shorten them unless you actually know that you can do it and still be able to re-assemble things.

    Never sand down a solder connection, as you don't want any of the abrasive or filings/dust in the cavity (you'll never get it all out). Buy some de-soldering braid and learn how to use it by practicing on something else. A de-soldering bulb might also be helpful.

    It is very likely that the only things you'll need to test for continuity/conductivity are the pickups as noted earlier.

    The interior of the cavity should already be shielded with shielding paint; that dark gray stuff. The electronics will be automatically connected to it when the pots are tightened, so there's nothing special to do there. There is a wire running from the bridge to the cavity and it should be connected to ground, so no worries there.

    Thanks, but I'm no king. And please remember that I am, in no way, speaking for G&L.

    For anyone reading this that would like to dive into their bass but have no clue about soldering (be honest!), give this page a read. De-soldering isn't covered, but maybe the author can be coaxed.

  7. Hugh Jass

    Hugh Jass

    Oct 10, 2008
    Canada eh
    It is more the "losing my bass for months" aspect of warranty that has me loth to go that route.

    As far as the sanding goes, I was planning on taking everything out of the cavity and then cleaning it all up with sanding and then alchohol to get a good solder joint. I was also planning on using those copper braids to desolder if i can find where I put em.

    I have wired some pretty funky stuff on cars before so that schematic doesn't look too bad. Like you say though, I will certainly check that pickup first incase it all revolves around that. At the very least I am going to go at those leads with a bag of zip ties. It looks like a robot threw up in there :D.

    I fully accept that the moment I bugger with anything in there my warranty on the electronics is nil. And I appreciate that all advise rendered is to be 'taken at my own risk' but most of all I appreciate all the advice! :D

    I still think G&L should hire you to handle their warranty dept. :bag:
  8. I understand completely. I could have taken a bridge issue to them on my L-2500 (stripped screws), but elected to fix/mod it myself for that very reason. It would only take me about 20 minutes to drive to the BBE office...

    Okay. The copper braid is probably all you'll need, especially if it's the fine-weaved stuff.

    Try this:


    It actually makes more sense than the stock wiring if the OBP-3 block is lifted out of the cavity, but there are still a lot of wires in there. The only wires remaining from the original are the pickup leads and they were not shortened for the project.

    Cool, and thanks for your understanding. I'm glad to help where I can, but it's only me doing it.

    Heh... I doubt that would happen, but thanks for the kind words.

  9. Hugh Jass

    Hugh Jass

    Oct 10, 2008
    Canada eh
    That photo with the obp-3 looks insane! It would be great to have a three band e.q. Looks like you switched the bass pot to a stack knob for bass/mid?

    I was thinking (not that I would ever do it) that the ultimate would be that setup plus converting the active/passive switch to a single coil/humbucker switch and put in a push/pull volume pot as a preamp on/off al'la Warwick.

    Hmmm, come to think of it my brother in law is an electrical engineering student, maybe I can get him to design a wiring harness.....

    Now I'm dreaming :D
  10. Bass/treble, which is, more-or-less, the norm for such things. Mid is a separate pot. I have it hardwired for low-mid control.

    What you see there is the DavePlaysBass single coil mod, providing series/single (outers)/parallel modes. EQ is 3-band, fully active boost/cut. Active/passive switch is just that. No EQ on passive. The entire package is a combination on Dave's and Aguilar's circuits.

    Works well, sounds huge, don't do it until/unless you get the current bugs worked out. Then you'll be at a known place.


  11. Hugh Jass

    Hugh Jass

    Oct 10, 2008
    Canada eh

    So I got myself a multimeter and here is what I found:

    I took the pickups right out of their plastic housings and tested the coils how you suggested.

    The first three coils read between 5.02 and 5.03 at 20K ohms.

    Now, the one that was not popping with the screwdriver (bridge pup top coil) read 0. I thought perhaps one of the leads had a break in it so I tested where the leads attach to the windings and still got a big goose egg while the other coils still read the same 5.XX when measured in this way.

    So, looks like a bad coil. Not sure if this is something that can be fixed or not.

    Any thoughts?
  12. spideyjg


    Mar 19, 2006
    San Diego
    0 as in 0 ohms (shorted coil) or no reading at all (open coil). Sounds like new pickup time.

    Disconnect the bad pickup from the circuit and see what happens to your tone problems.

  13. Were the pickups, particularly the one in question, isolated from the switch? Meaning that all four leads were disconnected? It's important that they were so that the readings you're getting are accurate.

    I'm not so concerned with the pickup that appears to be good. With respect to the other pickup; it is possible that a shorted switch can cause a coil to appear to be shorted when it really isn't. This is why it's important to have it out of circuit.

    If the pickup was disconnected when you did the test, and assuming that the 0 you read meant zero ohms (a dead short), then replacement is the best way to go because shorts are very difficult to find. It the zero was your meter's way of expressing infinite ohms (open circuit), then repair may be possible because a lot of breaks are near the surface of the overall coil or at the lead connections.

  14. Hugh Jass

    Hugh Jass

    Oct 10, 2008
    Canada eh
    The pickups were indeed right out of the bass and connected to nothing but the multimeter.

    The multimeter started at zero (when connected to nothing) and no change occured when the test leads were connected to the pickup leads or the pickups themselves. no reading. Appears like there is no circuit present at all. A short then?
  15. If this is the bad coil you're talking about, this would indicate that it's open.

    Meter geek stuff:

    An ohmmeter sends a small, known, amount of voltage through a circuit and measures it. It compares what it knows it sends with what it's reading. The difference is then calculated and displayed as resistance in ohms.

    In an open circuit - one that is broken - voltage is sent but no voltage is measured, so the meter reads it as infinite resistance to voltage flow because no voltage is flowing.

    In a shorted circuit, all the voltage sent is measured and the meter reads it as zero (0) ohms of resistance because all the voltage is flowing.


    If your coil is measuring zero (0) ohms, it's shorted someplace close to the leads. If your coil is measuring infinite resistance, it's an open coil with a break somewhere.

    Either way, it's a repair/replace deal for you. Go with whatever is easier.

  16. Hugh Jass

    Hugh Jass

    Oct 10, 2008
    Canada eh
    Upon second look here is what the meter reads:

    I have it set to 20K. When turned on it reads:

    1 _ . _ _

    on the good coils it reads:

    _ 5.03

    The bad one stays at:

    1 _ . _ _

    the _ represents a blank space. On any of the ohm settings it stays at 1 and the decimal place moves so 1 must be the current it sends.

    Hopefully this makes sense.
  17. spideyjg


    Mar 19, 2006
    San Diego
    Open coil.

    Put in the good one and see if that is your only problem.

    That would have caused issues whenever running that pickup or both in series.

    Less so in parallel.

  18. Hugh Jass

    Hugh Jass

    Oct 10, 2008
    Canada eh
    So I should reinstall the neck one in bridge position and try that?

    Pretty lazy tonight. Maybe tomorrow.

    On a positive note I emailed G&L who got back to me within a few hours :eek:. He is going to send me a return merchandise # or somesuch thing and then I am to mail in the bum pickup. :D

    Hopefully doesn't take too long.
  19. Up to you. I certainly wouldn't bother putting the bad one back in circuit.

    Very cool. On something like that, where you're just sending in a part to swap, it should be quick. I'll keep my fingers crossed.

  20. spideyjg


    Mar 19, 2006
    San Diego
    The pickups are identical so slap that good one back in and see if the bass fully functions with that one installed.

    You found a problem with that open coil but see if that was the cause of your woes.